Evaluation of the Acoustic Correlation Current Profiler on Discovery cruise 223

We present acoustic correlation current profiler (ACCP) data collected during Discovery cruise 223 and analyse its performance, in terms of %good, depth penetration, standard deviation of velocity per time / depth bin, as a function of various other parameters: wind speed, significant wave height, relative wind direction and ship speed. We compare ACCP currents with currents measured at the same time by acoustic Doppler current profilers (ADCPs), both vessel-mounted (VM-ADCP) and lowered (L-ADCP). Mainly the results are disappointing: the ACCP routinely profiles down only to about 600 m; there is near-zero data return in poor weather (moderate to high winds and waves); even deep profiles, down to ca. 1500 m on station in calm weather show much scatter and some divergence from L-ADCP profiles.